A numerical method for a global ocean model which does not need artificial islands or Fourier filtering at high northern latitudes is described. The method uses two grid schemes: one, for most of the ocean, is regular latitude-longitude; the other uses a rotated pseudo-latitude and pseudo-longitude scheme with the poles in the equatorial Pacific and Indian Oceans. The two grids defined by these coordinates communicate in the equatorial Atlantic. A method for communicating information between these is described briefly, and a test of the method is made using equatorial Kelvin and Rossby waves. The two-grid method is found to perform excellently (when compared with a similar problem using a simple latitude-longitude grid), so that the method may be considered validated for future use in a global model.